1. Field of the Invention
This invention generally relates to a data recording and reproducing apparatus. This invention particularly relates to an apparatus for recording and reproducing digital data on and from a tape-like recording medium by using a rotary head. In addition, this invention relates to a recording medium such as a tape-like recording medium loaded with digital data.
2. Description of the Related Art
There are video signals having a frame frequency of 29.97 Hz and video signals having a frame frequency of 30 Hz.
A background-art data recording and reproducing apparatus which is not prior art against this invention is capable of handling both a video signal of the 29.97-Hz type and a video signal of the 30-Hz type. The background-art apparatus includes a rotary head via which a video signal is recorded on a magnetic tape. The recording operation of the background-art apparatus can be changed between a 29.97-Hz mode for a video signal of the 29.97-Hz type and a 30-Hz mode for a video signal of the 30-Hz type. During the 29.97-Hz recording mode of operation of the background-art apparatus, a video signal of the 29.97-Hz type is recorded while the rotary head is rotated at a speed of 29.97 rps. During the 30-Hz recording mode of operation, a video signal of the 30-Hz type is recorded while the rotary head is rotated at a speed of 30 rps. A special flag is added to a video signal before the video signal is recorded. The special flag represents whether the recorded video signal is of the 29.97-Hz type or the 30-Hz type.
A reproducing side of the background-art apparatus includes a first equalizer designed exclusively for a video signal which has been recorded by the 29.97-Hz recording mode and also a second equalizer designed exclusively for a video signal which has been recorded by the 30-Hz recording mode. At a start of the reproduction of a video signal from the magnetic tape, a special flag is detected from the reproduced video signal. When the special flag represents that the reproduced video signal is of the 29.97-Hz type, the rotary head is rotated at a speed of 29.97 rps. In addition, the reproduced video signal is processed by the first equalizer. When the special flag represents that the reproduced video signal is of the 30-Hz type, the rotary head is rotated at a speed of 30 rps. In addition, the reproduced video signal is processed by the second equalizer.
Since the background-art apparatus has two equalizers (the first and second equalizers), the structure of the background-art apparatus is complicated. In addition, the background-art apparatus is expensive.
It is a first object of this invention to provide an improved data recording and reproducing apparatus.
It is a second object of this invention to provide an improved recording medium.
A first aspect of this invention provides a data recording and reproducing apparatus comprising a rotary head for recording a signal on a tape-like recording medium while successively forming tracks thereon, and for reproducing a signal from the tape-like recording medium, wherein each of the tracks has a front margin area, an effective data area, and a rear margin area; first means for generating a flag representing which of different speeds the rotary head rotates at; second means for inserting the flag generated by the first means into the signal before the signal is recorded on the tape-like recording medium by the rotary head to record the flag on the effective data area; and third means for maintaining a data rate of the signal recorded on the tape-like recording medium at a constant rate independent of which of the different speeds the rotary head rotates at, and for changing an amount of data recorded on the rear margin area in response to which of the different speeds the rotary head rotates at to cause the tracks to be equal in length independent of which of the different speeds the rotary head rotates at.
A second aspect of this invention provides a data recording and reproducing apparatus comprising a rotary head for recording a signal on a tape-like recording medium while successively forming tracks thereon, and for reproducing a signal from the tape-like recording medium, wherein each of the tracks has a front margin area, an effective data area, and a rear margin area; first means for generating a flag representing which of different speeds the rotary head rotates at; second means for inserting the flag generated by the first means into the signal before the signal is recorded on the tape-like recording medium by the rotary head to record the flag on the effective data area; third means for maintaining a data rate of the signal recorded on the tape-like recording medium at a constant rate independent of which of the different speeds the rotary head rotates at, and for changing an amount of data recorded on the rear margin area in response to which of the different speeds the rotary head rotates at to cause the tracks to be equal in length independent of which of the different speeds the rotary head rotates at; an equalizer for subjecting the signal reproduced by the rotary head to a waveform equalization process, and for outputting a signal representing a result of the waveform equalization process; a phase-locked loop for generating a channel clock signal on the basis of the signal outputted by the equalizer; and fourth means for extracting the flag from the signal outputted by the equalizer, for controlling rotation of the rotary drum in response to the extracted flag, and for controlling feed of the tape-like recording medium in response to the extracted flag to maintain a channel bit rate of the signal reproduced by the rotary head at a constant rate independent of which of the different speeds the rotary head rotates at.
A third aspect of this invention is based on the first aspect thereof, and provides a data recording and reproducing apparatus wherein the different speeds relate to two different frequency values between which a frame frequency of the signal recorded by the rotary head is changeable.
A fourth aspect of this invention provides a tape-like recording medium having tracks successively formed by a rotary head while a signal is recorded on the tracks by the rotary head, wherein each of the tracks has a front margin area, an effective data area, and a rear margin area, the effective data area being loaded with a flag representing which of different speeds the rotary head rotates at, wherein recording of the signal on the tracks by the rotary head is executed under conditions where a data rate of the signal recorded by the rotary head is maintained at a constant rate independent of which of the different speeds the rotary head rotates at, and an amount of data recorded on the rear margin area is controlled in response to which of the different speeds the rotary head rotates at to cause the tracks to be equal in length independent of which of the different speeds the rotary head rotates at.
A fifth aspect of this invention provides an apparatus comprising first means for recording a digital video signal on a recording tape while successively forming tracks on the tape, the digital video signal having a changeable frame frequency, the digital video signal having a sequence of 1-track-corresponding portions assigned to the respective tracks, wherein each of the 1-track-corresponding portions includes a margin signal; second means for maintaining a data rate of the digital video signal which is being recorded by the first means at a constant rate independent of the frame frequency of the digital video signal; and third means for changing a number of bits of the margin signal and a recording density of the digital video signal on the tape in response to the frame frequency of the digital video signal.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides an apparatus further comprising fourth means for generating a flag representing whether the frame frequency of the digital video signal is equal to a first predetermined value or a second predetermined value; and fifth means for inserting the flag generated by the fourth means into the digital video signal before the digital video signal is recorded by the first means.
A seventh aspect of this invention is based on the fifth aspect thereof, and provides an apparatus wherein the margin signal comprises a dummy signal.
An eighth aspect of this invention provides an apparatus comprising first means for reproducing a digital video signal from a recording tape, the digital video signal having a frame frequency changeable between a first predetermined value and a second predetermined value, the digital video signal containing a flag representing whether the frame frequency of the digital video signal is equal to the first predetermined value or the second predetermined value; an equalizer for subjecting the digital video signal reproduced by the first means to a waveform equalization process independent of whether the frame frequency of the digital video signal is equal to the first predetermined value or the second predetermined value, and for outputting a signal representing a result of the waveform equalization process; second means for detecting the flag in the signal outputted by the equalizer; and third means for controlling the reproducing of the digital video signal by the first means in response to the flag detected by the second means to maintain a data rate of the digital video signal which is being reproduced by the first means at a constant rate independent of whether the frame frequency of the digital video signal is equal to the first predetermined value or the second predetermined value.